Embodiments of the invention relate generally to a direct current (DC) power system and more specifically to a DC power system for marine applications.
In the last few decades, marine traffic has increased substantially across the world due to tremendous rise in cargo transport vessels, warships, offshore oil ships, passenger ships etc. These vessels or ships have many electrical loads on board. Variable speed electric drives for pumps, fans, electric propulsion installations, lighting and air conditioning are some examples of the electrical loads on board of a ship. The electrical loads operate at various different voltages and frequencies, and thus need separate electric power supplies.
Most of the ships use alternating current (AC) power system architecture. However, more recently some ships are using DC power system architecture including energy storage devices or electrical generators to meet the demands of the plurality of electrical loads. If a load needs alternating current (AC) power supply, the DC power may be converted into AC power with help of power electronic converters. Similarly, if the electrical generator is AC then the AC power may be converted into DC power via power electronic converters. Generally, a plurality of generators supplies power to a plurality of DC buses which in turn supply power to a particular electrical load. There are examples where a single DC bus can also provide power to the entire ship electrical load.
Challenges with conventional DC power system include integration of multiple DC buses with different voltage levels, isolating the faults in the DC power system in a very short time and integrating the various energy storage devices and generators. For these and other reasons, there is a need for the present DC power system for marine applications.